Field of Invention
The present invention relates to a power supply system capable of performing a short circuit detection and a bad connection detection; particularly, it relates to such a power supply system capable of detecting abnormal but not severe conditions which lead to undesirable power loss, such as weakly short circuit and weakly bad connection conditions, and a detection method and a power converter thereof.
Description of Related Art
Please refer to FIGS. 1A and 1B. FIG. 1A shows a block diagram of a conventional power supply system. FIG. 1B explains how an abnormal but not severe condition occurs in the prior art of FIG. 1A which leads to power loss. The conventional power supply system 10 comprises a power converter 11, a cable 12 and an electronic device 13. A port 112 of the power converter 11 is connected to a port 121 of the cable 12. A port 132 of the electronic device 13 is connected to another port 122 of the cable 12. When the power converter 11, the cable 12 and the electronic device 13 are connected in serial, power lines 17 and 18 form a loop to deliver the power. The cable 12 further includes a signal line 14, for data transmission between the power converter 11 and the electronic device 13. The signal line 14 can be, for example but not limited to, a differential signal line.
As shown in FIG. 1B, when an unwanted material such as dust, dirt, thread, etc. falls on or in the ports 112, 121, 122 and/or 132, the power lines 17 and 18 may be “weakly short-circuited”—i.e., a short-cut current path is formed between the power lines 17 and 18, but the electrical connection is weak, so there is not a huge amount of current flowing through this short-cut current path. Such “weakly short circuit” is illustrated by the resistors R11, R121, R122 and R13 in the figure. Although there is not a huge amount of current flowing through the short-cut current path, this abnormal condition still leads to power loss, and if this abnormal condition is not well controlled, it can be very dangerous.
Besides, if the power lines 17 and 18 does not have a good quality, or a bad connection occurs between the ports, even though the bad connection is not so severe to cause an open-circuit, this abnormal condition will also lead to power loss. The bad connection is illustrated by the resistors R1′, R2′, R3′ and R4′ in the figure.
Because the “weakly short circuit” and “bad connection” usually do not lead to fully short-circuit or complete open-circuit, the prior art did not propose an effective solution to address this issue.
The prior art U.S. Pat. No. 8,498,087 and U.S. Pat. No. 8,339,760 provide an approach to solve the above-mentioned problem by detecting whether there is abnormal temperature increase in the cable. However, to do so, an additional heat detection signal line is required, which is not compatible to the current standard cable, and also leads to a higher manufacturing cost. Moreover, before an abnormal temperature increase becomes detectable, unwanted power loss and other problems have already happened for a long time. Therefore, the above-mentioned prior art patents do not practically solve the problem.
In view of the above, to overcome the drawbacks in the prior art, the present invention proposes a power supply system capable of detecting an abnormal condition such as a weakly short circuit and a bad connection, which leads to undesirable power loss.